Polyvinyl acetate and acrylic latex paints



United States Patent 3,215,660 POLYVINYL ACETATE AND ACRYLIC LATEXPAINTS Loren A. Bryan, Elizabethton, Tenn, and William A. Tidridge,Fanwood, N.J., assignors to FMC Corporation, New York, N .Y., acorporation of Delaware No Drawing. Original application Aug. 8, 1961,Ser. No. 129,983, now Patent No. 3,154,510, dated Oct. 27, 1964. Dividedand this application Mar. 4, 1964, Ser. No. 349,475

7 Claims. (Cl. 26029.6)

The present invention is concerned with increasing the adhesion of filmsof water-thinned, polyvinyl acetate and acrylic based latex paints tosurfaces to which they are are applied.

This application is a divisional of Serial No. 129,983, now Patent No.3,154,510, filed on August 8, 1961, in the name of Loren A. Bryan andWilliam A. Tidridge, entitled Polyvinyl Acetate and Acrylic LatexPaints.

Paints based on synthetic resin latices have become increasinglyimportant as surface coatings. These latex paints are very advantageousbecause their quick drying and their good surface covering propertiesobviate the skillful painting techniques required in applying oil-basedpaints.

The principal latex used in these paints is based on a butadiene-styrenecopolymer. Latices of the polymers of acrylic acid esters and thepolymers of polyvinyl acetate when applied as surface coatings formfilms which have good physical properties including flex resistance,resistance to oil, and marked durability. However, these latices havenot enjoyed wide-spread acceptance despite their desirable properties,because of the poor adhesion their film exhibit to various basesurfaces. As a result, there has been a serious need for a method ofimproving the adhesion of the polyvinyl acetate and acrylic acid esterwater-based paints to base surfaces coated with these paints.

It is an object of the present invention to increase the adhesion ofpolyvinyl acetate and acrylic acid ester latex emulsions to painted basesurfaces without otherwise affecting the other desirable properties ofthe paint.

These and other objects will be obvious from the following disclosure.

It has now been found unexpectedly that Water-thinned latex paints whichcontain either a polyvinyl acetate base, or an acrylic acid ester base,have increased adhesion to base surfaces coated with these paints, whenthey contain an organic salt which is either a barium cyanurate, bariumphytate, barium sulfostearate, barium sulfopalmitate or bariumdodecylbenzene sulfonate, in an amount of about 0.5 to 1% by weight.

The barium cyanurates and barium phytate when employed with polyvinylacetate base paints also increase the corrosion resistance of thesepaints. This feature is described and claimed in our co-pendingapplication Corrosion Resistant Paints, Serial No. 129,958, now PatentNo. 3,137,583, filed on August 8, 1961.

The water-thinned paints defined above are saturated polymeric materialshaving no iodine number as distinguished from natural latex emulsionsand butadienestyrene copolymer emulsions whose polymeric make-upcontains unsaturated groups which give sizable iodine numbers. Theinstant paints have the base ingredient suspended in the form of anaqueous emulsion. When this aqueous emulsion is applied to a surface,the water evaporates and the resulting latex particles coalesce into alinear film polymer, without crosslinking. Typical formulations foracrylic acid ester based emulsions are given below as Formula I andFormula II.

3,215,650 Patented Nov. 2, 1965 FORMULA I Acrylic latex white paint 1Ingredient: Lb. gal. Titanium oxide, rutile 2.137 Calcium carbonate0.471 Magnesium silicate 0.829 Diatomaceons silica 0.925 Acrylic latex(46NV) 2 4.073 Carboxyme'thyl cellulose, 5% aqueous 0.159 Tamol 731, 10%aqueous 0.065 Acrysol A-3, 10% aqueous 4 0.065 Boric acid 0.063Diethylene glycol 0.084 Triton X-102 5 0.022 Polyglycol P-1200 6 0.021Ammonium hydroxide, 28% aqueous 0.043 Water 2.491

Basic formulation from Acrylic Emulsion Technology, p. 9, Rohm and Haas.

2 The acrylic latex polymer was made up from a mixture of 284 ml. ofdeionized Water, 24 grams of Triton X-200 (a. 28% alkylaryl sulfonateemulsifier in aqueous solution), 4 ml. of a solution of 0.3 gram ofFeSO4-7H2O in 200 ml. of water, 1 gram of ammonium b'isulfate, and 200grams of ethyl acrylate. This mixture was placed in the flask and 1 gramof sodium metabisulfite and 5 drops of 70% tertiary butyl hydrogenperoxide was added to the mixture. Within 2 to 5 minutes the temperaturewent up to 89 C. The mixture was permitted to stand for 15 minutes atwhich time 98% of the acrylic resin had polymerized. The result was a46% solids emulsion.

3 A sodium salt of a high molecular weight polycarboxylie acid in a 10%aqueous solution.

*Water soluble thickener composed of a 10% solution of ammoniumpolyacrylate.

5 An allrylaryl polyether alcohol.

Polyethylene glycol.

FORMULA II Acrylic latex white paint Ingredient: Parts by weight Water37.3 Ethylene glycol 25.0 Triton CF-10 1 4.0 Tamol 731 8.6 Bubblebreaker 748 4.0 Titanox RA-NC (TiO 175.0 Snowflake Whiting 3 244.0Acrylic latex (46NV) 4 574.7 3% Methocel 4000 (65H6) 65.7 Ammoniumhydroxide 2.0 PMA-18 6 9.0

1 Polyoxyethylene ether of octyl benzene.

A sodium salt of a high molecular weight polycarboxylic acid in a 10%aqueous emulsion.

3 Calcium carbonate.

The acrylic latex polymer was made up from a mixture of 284 ml. ofde-ionized water, 24 grams of Triton X-200 (a 28% alkylaryl sulfonateemulsifier in aqueous solution), 4 ml. of a solution of 0.3 gram ofFeSOl-7HzO in 200 ml. of water, 1 gram of ammonium bisulfate, and 200grams of ethyl acrylate. This mixture was placed in the flask and 1 gramof sodium metabisulfite and 5 drops of 70% tertiary butyl hydrogenperoxide was added to the mixture. Within 2 to 5 minutes the temperaturewent up to 89 C. The mixture was permitted to stand for 15 minutes atwhich time 98% of the acrylic resin had polymerized. The result was a46% s ids emulsion.

Methylcellulose with a viscosity of 4000 cps.

G Plienylmercuric acetate.

A typical formulation for a polyvinyl acetate based latex emulsion isgiven in Formula III.

FORMULA III Polyvinyl acetate white latex paint Ingredient: Lb. gal.Titanium oxide, rutile 2.472 Silica 0.438

Calcium silicate 0.461

Lb./gal. Polyvinyl acetate emulsion (*5 NV) 1 3.000 Tamol 73 1, aqueous0.034 Dibutyl phthalate 0.247 Hexylene glycol 0.185 Ethylene glycol0.309 Pluronic L62 0.025 Aerosol OT, 75% aqueous -2 0.034 Methocel 4000cps, 2% aqueous 5 2.247 Water 1.657

1 The 55% non-volatile polyvinyl acetate emulsion was prepared by mixingtOgetlier 45 grams of water, 1% Triton X200 (21 28% alkylaryl sulfonateemulsifier in aqueous solution) and 1% of a low viscosity polyvinylalcohol in a flask equipped with a reflux condenser. To this mixture wasadded a half-gram of ammonium persulfate and 5 parts of vinyl acetate.The mixture was heated to a temperature of about 90 C. The balance ofthe vinyl acetate (50 parts) was added while refluxing over a period ofseveral hours. The resulting emulsion contained 55% non-volatilematerial and had a viscosity .of about 1200-1400 cps.

A sodium salt of a high molecular Weight polycarboxyhc acid in a 10%aqueous solution.

8 A polyethylene oxidepolypropylene oxide condensate with a molecularweight of about 2500.

*Dioctyl ester .of sodium sulfosuccinic acid.

5 An aqueous methyl cellulose solution having a viscosity of 4000 cps.

The increase in adhesion varies depending upon which of two types oflatex emulsions is employed, and wh1ch barium salt is added to theemulsion. In general, the barium cyanurate salts have been found mosteffective in the acrylic latex emulsions. The barium cyanurates whichcan be employed are barium hydrogen cyanurate, barium di-hydrogencyanurate, barium cyanurate, and mixtures of the above. Of the bariumsalt additives employed with the polyvinyl acetate latex emulsions,barium cyanurates, barium phytate and barium sulfostearate were the mosteffective.

The following examples illustrate the improved adhesion obtained by theinclusion of the specified barium salts and are presented asrepresentative of the present invention but are not intended aslimitative thereof.

EXAMPLE 1 The paint formulation found in Formula I, given above, wasprepared in the following manner. The water was weighed into a 1-literbeaker and there was added, with stirring, in the order given: 5%aqueous carboxymethyl cellulose solution, polyglycol P-1200, 28% ammonium hydroxide, Acrysol A3, 10% Tamol 731, boric acid, Triton X-102and diethylene glycol. This mixture was stirred until it had reached aworkable homogeneity. Stirring was continued and there was added in theorder: titanium oxide, calcium carbonate, magnesium silicate anddiatomaceous silica. The mixture was stirred until a uniform consistencywas obtained. It was passed through a Morehouse mill two times. The millslurry was collected in a tared beaker, weighed and a quantity ofacrylic latex based on the paste yield was added with stirring. Stirringwas continued until 20 minutes had elapsed. The pH of the beaker wasadjusted to 9.4 by the addition of small amounts of ammonium hydroxidesolution.

The control formulation used in the example was made up as describedabove. The experimental formulations were made up exactly as set forthabove except that each of the barium salts designated in Table I wasadded to the formulations during the blending operation, after theaddition of the calcium carbonate but before the addition of themagnesium silicate. The control formulations and the experimentalformulations containing the various salts were applied to the surface ofbare, mild, steel, metal test panels and were tested for adhesion bymeans of a Hoffman Scratch-Hardness Tester. This instrument consist of agraduated beam equipped with weights that exert a force on a hollowcylindrical scratch tool. These are mounted on a flat carriage with 4wheels that can be drawn over a flat painted surface. The adhesion ismade by cutting a line all the way through the test film down to themetal substrate. The edge of the scratching tool is placed in the cutand moved at right-angles to the 4c cut. The adhesion test is the weightin grams of force on the scratching tool required to cause the film tobe removed cleanly from the substrate. Details for the use andmaintenance of the instrument are provided in Instructions forHoffman-Scratch Hardness Tester, PH 1750A, Gardner Laboratory, Inc.(December 1957). The results of the testing are reported in Table I.

EXAMPLE 2 The paint formulations in Formula III were prepared in thefollowing manner. The polyvinyl acetate interior white paint wasobtained by preparing a mixture of the prepared polyvinyl emulsion,plasticizers and wetting agents into a Paint Base. Simultaneously, amixture of water and pigment with thickener and dispersion agents ismade up as a Pigment Slurry. The paint is prepared by adding the PaintBase to the Pigment Slurry.

The Paint Base was prepared by mixing in the following ordcr, and withstirring, the hexylenc glycol, ethylene glycol, Pluronic L-62, AerosolOT, dibutyl phthalate and about 39% of the water required in FormulationII. After mixing 5 minutes, the prepared polyvinyl emulsion was addedgradually and the entire mixture was stirred for 30 minutes. The PigmentSlurry was prepared by adding the remaining 61% of the water required bythe formulation in a beaker and 10% aqueous Tarnol 731, 2% aqueousMethocel, titanium oxide, diatomaceous silica and calcium silicate. Theadditions were made with constant stirring until the slurry was smoothand free of lumps.

The finished paint was prepared by adding the Paint Base to the PigmentSlurry with constant stirring. The mixture was stirred until it appearedhomogeneous and was then passed twice through a Day 3-roll mill until afineness of grind of 5H was obtained.

The designated H refers to the Hegman grind gauge which was used in thedetermination. The method for using this gauge is described by Gordonand Dolgin in Surface Coatings and Finishes, Chemical PublishingCompany, New York (1954). The proper use of this instrument is furtherreported in an article by Doubleday and Barkman, printed in the Paint,Oil and Chemical Review (June 22, 1950).

The control formulation used in this example was made up exactly asdescribed above. The experimental formulations were made up exactly asset forth above except that each of the barium salts designated in TableI was added when the Paint Base was added to the Pig ment Slurry. Theformulations were tested as set forth in Example 1 and the results arereported in Table I.

The paint formulations in Formula II were prepared in the same manner asExample 1. These formulations were tested by coating a sample of thetest paint over a glossy linseed oil exterior house paint film coated ona lacquered chart. The adhesion of the test paint to the oil-paintedglossy surface was tested by trying to separate the test coating fromthe glossy paint surface by scratching with a sharp surface. The resultsare given in Table II.

excellent; 9very good; 8good; 6fair1y good; 4fair; 2p0or; 0failure.

The present class of barium salts are effective in improving theadhesion of these latex paints to bare metal surfaces as well as tosurfaces which have coatings of paint. This is demonstrated in Table IIwherein the adhesion of the latex paint to a house-painted surface wasimproved by the addition of one of the presently employed barium salts.It is thus seen that this increased adhesion is obtained even withsurfaces which are difiicult for paints to adhere to. As a result of thepresent additives, these latex paints can be employed in new fields ofapplication which heretofore were closed to these latex paints becauseof their poor adhesion.

The barium additives materially increase the hardness of the latex paintfilms. The increase in hardness is on the order of between 100% to 250%in both the acrylic latex and the polyvinyl acetate latex. This addedhardness is most desirable since it affords a film which is adherent tothe base and which also can resist abrasion and impact stress.Resistance to impact and abrasion is very important when the paints areapplied as floor coatings and are subject to severe abrasion and wear.

While the improvement in the adhesion of the latex paints defined aboveis the prime interest of this application, it has been noted that thesebarium additives also increase the adhesion of many solvent-thinnedpaints. Typical of these are the air-drying oil base, alkyd resin base,epoxy base, and other similar non-water-thinned latex paints. Thisincreased adhesion is obtained without affecting the other desirableproperties of the solventthinned paints, and is useful where increasedadhesion is necessary.

Pursuant to the requirements of the patent statutes, the principle ofthis invention has been explained and exemplified in a manner so that itcan be readily practiced by those skilled in the art, suchexemplification including what is considered to represent the bestembodiment of the invention. However, it should be clearly understoodthat, within the scope of the appended claims, the invention may bepracticed by those skilled in the art, and having the benefit of thisdisclosure, otherwise than as specifically described and exemplifiedherein.

What is claimed is:

1. The method of increasing the adhesion of waterthinned poly-ethylacrylate base latex paints comprising adding to said paints a bariumsalt selected from the group consisting of barium cyanurates, bariumphytate, barium sulfostearate, barium sulfopalmitate and bariumdodecylbenzene sulfonate in the amount of about 0.5 to about 1% byweight.

2. A composition of matter comprising an adherent water-thinnedpoly-ethyl acrylate base latex paint containing a barium salt selectedfrom the group consisting of barium cyanurates, barium phytate, bariumsulfostearate, barium sulfopalrnitate and barium dodecylbenzenesulfonate, said salt being present in the amount of about 0.5 to about1% by weight.

3. A composition of matter comprising an adherent water-thinnedpoly-ethyl acrylate base latex paint con taining from about 0.5 to about1% by weight of barium cyanurate.

4. A composition of matter comprising an adherent water-thinnedpoly-ethyl acrylate base latex paint containing from about 0.5 to about1% by weight of barium phytate.

5. A composition of matter comprising an adherent water-thinnedpoly-ethyl acrylate base latex paint containing from about 0.5 to about1% by weight of barium sulfostearate.

6. A composition of matter comprising an adherent water-thinnedpoly-ethyl acrylate base latex paint containing from about 0.5 to about1% by weight of barium sulfopalmitate.

7. A composition of matter comprising an adherent water-thinnedpoly-ethyl acrylate base latex paint containing from about 0.5 to about1% by weight of barium dodecylbenzene sulfonate.

No references cited.

MURRAY TILLMAN, Primary Examiner.

1. THE METHOD OF INCREASING THE ADHESION OF WATERTHINNED POLY-ETHYLACRYLATE BASE LATEX PAINTS COMPRISING ADDING TO SAID PAINTS A BARIUMSALT SELECTED FROM THE GROUP CONSISTING OF BARIUM CYANURATES, BARIUMPHYTATE, BARIUM SULFOSTEARATE, BARIUM SULFOPALMITATE AND BARIUMDODECYLBENZENE SULFONATE IN THE AMOUNT OF ABOUT 0.5 TO ABOUT 1% BYWEIGHT.